Integrated fuel cell and fuel conversion apparatus

ABSTRACT

An apparatus, process and use for making hydrogen from a hydrocarbon feedstock and steam using heat stored in a vessel followed by the regeneration of the vessel to restore the heat. Regeneration is done by preheating within the vessel a hydrogen purge gas and regeneration combustion products recycle and mixing the preheated gases with an oxygen containing gas so that they combust within the vessel in a fuel rich mode and heat material disposed in the vessel. This is the heat which is used in converting the hydrocarbon feedstock to hydrogen. The regeneration combustion products are recycled (and substituted for the cooling capacity of the oxygen containing gas) to recover the heat remaining in the vessel following the hydrogen make cycle simplifying reactor bed design and improving operational flexibility. The process is applied to provide hydrogen to a fuel cell.

1. Technical Field

This invention relates to methods and apparatus for producing a hydrogencontaining gas from a hydrocarbon feedstock.

2. Background Art

In the prior art, producing a hydrogen containing gas, such as hydrogen,from a hydrocarbon feedstock is typically accomplished by passing thefeedstock (and steam if the conversion process is stem reforming)through catalyst filled tubes disposed within a furnace. Fuel and airare burned within the furnace to provide heat for the catalytic reactiontaking place within the tubes. In order to improve the efficiency ofsuch apparatus some efforts have been directed to improving theuniformity of heat distribution to the tubes within the furnace whileminimizing the amount of energy used to produce each unit of hydrogencontaining gas. For example, in commonly owned U.S. Pat. No. 4,098,587to R. A. Sederquist et al the reaction tubes are clustered closelytogether in a furnace, with baffles and sleeves surrounding each tube toimprove heat transfer from the combusting gases in the furnace into thecatalyst beds. Each catalyst bed is annular; and a portion of the heatin the product gases leaving the bed is returned to the bed to furtherthe reaction process by flowing these product gases through a narrowannular chamber along the inside wall of the annular catalyst bed. Theexample given in column 7 of the Sederquist el al patent indicates thatan overall reactor thermal efficiency of 90% was achieved with theapparatus described therein. Other commonly owned patents of a somewhatsimilar nature are U.S. Pat. Nos. 4,071,330; 4,098,588; and 4,098,589.

One drawback of the approaches taken in all of the foregoing patents isthat the heat for the conversion process is still provided indirectly bymeans of heat transfer through reactor walls. Also, a considerableamount of heat energy leaves the furnace with the furnace exhaust gases.Although some of this heat can be recovered and used for other purposes,such as producing steam, it would be more beneficial if this heat energycould be used in the conversion process.

Another process and apparatus for the catalytic conversion ofhydrocarbons by steam is shown and described in a paper titled"Conversion Catalytique et Cyclique Des Hydrocarbures Liquides etGazeux" published by Societe Onia-Gegi. That system comprises a firstvessel including a first heat exchange chamber, followed by a secondvessel containing a catalyst bed, followed by a third vessel including asecond heat exchange chamber. In operation, steam is introduced into thefirst vessel and is preheated as it passes through hot checkerbricksdisposed within the chamber. Downstream of the checkerbricks thepreheated steam is mixed with a hydrocarbon feedstock and the mixturepasses into the second vessel containing a heated catalyst bed by meansof a conduit interconnecting the two vessels. Conversion takes place asthe mixture passes through the heated catalyst bed. Hot conversionproducts leave the second vessel and enter the third vessel, whereuponthe hot conversion products give up heat to checkerbricks which aredisposed therein. The conversion products may then be stored or useddirectly.

When the temperatures in the first heat exchange chamber and in thecatalyst bed are too low to convert the feedstock, the apparatus isswitched to a regeneration cycle. In the regeneration cycle air isintroduced into the third vessel and is preheated as it passes throughthe checkerbricks disposed therein which were heated during theconversion cycle. Downstream of the checkerbricks a fuel, such as oil,is mixed with the preheated air and combusts. In order to keepcombustion temperatures within acceptable limits, air in excess of thatrequired for stoichiometric combustion is used. The hot combustionproducts are directed into the second vessel and pass through thecatalyst bed, therein heating the same. This is the heat which is usedduring the conversion cycle. Because of the excess air, the catalyst bedis oxidized, although this is not desirable. (During the conversion modeof the cycle the oxidized catalyst is reduced back to the metal; thisrequires use of some of the hydrogen being manufactured, and has anegative impact on efficiency).

After passing through the catalyst bed the combustion products aredirected into the first vessel and give up additional heat to thecheckerbricks disposed therein. This is the heat which is used topreheat the steam during the conversion cycle.

Commonly owned U.S. Pat. No. 3,531,263 describes an integrated reformerunit comprised of a can-type structure which houses the reactioncomponents of a system for converting hydrocarbon feedstocks tohydrogen. This compact apparatus, in one embodiment, comprises a centertube containing a volume of reform catalyst, followed immediately by aregion of heat transfer packing material, followed by a volume of shitconversion catalyst. Surrounding the tube over its entire length is anannular passage. Air is introduced into the end of the annular passageadjacent the shift catalyst volume of the center tube. It is mixed withfuel approximately adjacent the interface between the heat transferpacking material and the reform catalyst. The fuel and air burn andtravel further downstream around the outside of that portion of thecenter tube carrying the reform catalyst. Simultaneously a mixture of ahydrocarbon feedstock and water enter the center tube at the reformcatalyst end. Steam reforming takes place within the catalyst bed withthe heat being provided by the hot combustion products flowingcountercurrent in the annulus around the outside of the tube. As thereform products leave the catalyst bed they give up heat to the heattransfer packing material in the next following region. This heat isused to preheat the air flowing around the outside of this heat transferregion before the air is mixed with the fuel and burned. The cooledproducts from the packing material region then pass through the shiftconversion catalyst volume whereupon carbon monoxide present therein isconverted to additional hydrogen and carbon dioxide. This reaction isexothermic, and the heat produced thereby preheats the air flowingaround the outside of the tube.

While the foregoing apparatus is compact, and careful attention has beengiven to the overall heat balance and heat requirements of the hydrogengenerating reaction, most heat transfer is still indirect and asignificant amount of the heat energy generated within the apparatus,leaves the apparatus with the combustion exhaust and the reformproducts.

Commonly owned U.S. Pat. Nos. 4,200,682; 4,240,805; and 4,293,315, thedisclosures of which are hereby incorporated by reference also relate tomethods and apparatus for producing a hydrogen containing gas from ahydrocarbon feedstock. In particular, in U.S. Pat. No. 4,200,682 acontinuous supply of hydrogen is provided to a fuel cell from a pair ofreaction vessels by making hydrogen in one of the vessels whilesimultaneously regenerating the other vessel, and then reversing thefunction of the vessels. In the step of making hydrogen, a hydrocarbonfeedstock and steam flows into a vessel and is cracked and steamreformed using heat which was generated during the regeneration cycleand stored in packing material. The step of regenerating the vesselincludes directing the fuel cell electrode exhaust and an oxygencontaining gas into the vessel, preheating the fuel electrode exhaustand oxygen containing gas separately within the vessel, and mixing thesepreheated gases and combusting them within the vessel. The step ofpreheating is accomplished using the heat stored within materialdisposed within the vessel during the making of hydrogen. Although thiscyclic reformer system functions well, the regeneration was typicallyaccomplished by passing the oxygen containing gas through conduits toseparate the oxygen from the fuel electrode exhaust during the preheatstage. However, the use of these conduits can add engineering designproblems and additional cost.

Accordingly, there has been a constant search in this field of art forcyclic reformer systems that incorporate alternative regenerationsystems.

DISCLOSURE OF THE INVENTION

It is one object of the present invention to provide a novel, highlyefficient method and apparatus for converting a hydrocarbon feedstockinto a hydrogen containing gas.

A further object of the present invention is a compact apparatus for theconversion of a hydrocarbon feedstock to a hydrogen containing gas.

Yet another object of the present invention is a method and means forefficiently integrating a fuel cell within an apparatus for converting ahydrocarbon feedstock to hydrogen.

In a catalytic reaction vessel, a hydrogen containing gas is made from ahydrocarbon feedstock and steam using heat stored in the vessel and thevessel is then regenerated to restore the heat used, the regenerationbeing done by preheating a hydrogen purge gas and regenerationcombustion products recycle and mixing these preheated gases with anoxygen containing gas so that they combust within the vessel in a fuelrich mode and heat material disposed therein.

Hydrogen purge gas, as that phrase is used herein, is defined as a gascontaining at least some hydrogen for the purpose of combusting with theoxidant which is introduced in the reaction vessel during regeneration.The hydrogen purge gas may also contain other combustibles, such ascarbon monoxide and methane. Heavier hydrocarbons are undesirable (butnot necessarily intolerable) since they could form carbon upon cracking.The purge gas may also include noncombustibles, such as carbon dioxide,water vapor and nitrogen. Examples of hydrogen purge gases are: purehydrogen; effluent from the fuel or anode compartments of acid, base ormolten carbonate fuel cells; and the purge effluent from well knownpressure swing absorption type hydrogen purification systems.

In a preferred embodiment hydrogen is the desired product gas. Thereaction vessel has three zones arranged in sequence. During the makingof the hydrogen (i.e., make mode) the hydrocarbon feedstock and steamare preheated within the first zone which is filled with material whichwas heated during regeneration of the reaction vessel. Gasification(i.e., cracking and reforming), of the feedstock and steam mixture takesplace within the next following second zone of heated material whichincludes a region of reform catalyst. The gas so produced is then cooledin a lower temperature third zone, thereby increasing the temperature ofthe material within the third zone. The heat used in making the hydrogenis restored by regenerating the reaction vessel (i.e., regenerationmode). Regenerating is accomplished by preheating a hydrogen purge gasand regeneration combustion products recycle using the sensible heatstored during the make mode in material disposed in the vessel. Thesegases are mixed with an oxygen containing gas so that they combustwithin the second of the above-mentioned zones to reheat the material inthat zone. Combustion products from the second zone are then cooled bypassing them through the first zone, whereby material in the first zoneis reheated.

The present invention is very compact and highly efficient. All of theenergy expended in the method is utilized to directly convert thefeedstock to the desired hydrogen containing gas, which is usuallyhydrogen. Virtually all heat transfer is direct, which eliminates lossestypically associated with indirect heating and cooling. Preheating ofboth hydrogen purge gas and combination products recycle without usingan external heat source also increases efficiency by recovering themaximum amount of heat from the product gas of the make mode. Maximizingpreheating minimizes the amount of hydrogen purge gas which must beburned to provide process heat, which also increases efficiency. Thermalefficiencies of 95% and perhaps higher can be obtained by the method ofthe present invention.

Recycling of the regeneration combustion products is also an importantaspect of the present invention. This eliminates the need for passingthe oxygen containing gas through the third zone in order to recover theheat remaining in the vessel following the hydrogen make cycle. This inturn eliminates the need for conduits to separate the oxygen containinggas from the hydrogen purge gas.

If a continuous supply of a hydrogen containing gas is required, twoseparate reaction vessels may be used simultaneously, with the firstvessel making the hydrogen containing gas while the second is beingregenerated, and then switching the mode of operation of each vessel sothat the first is being regenerated while the second is making thehydrogen containing gas.

This invention is particularly useful for supplying hydrogen to theanode of a fuel cell. In a preferred arrangement, while one reactionvessel is supplying the hydrogen, the other vessel may be regeneratedusing the anode exhaust as the hydrogen purge gas.

The foregoing and other objects, features and advantages will beapparent from the specification, claims and from the accompanyingdrawings which will illustrate an embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front view, partly broken away, of a pair of catalyticreaction vessels according to the present invention.

FIG. 2 is a schematic diagram of catalytic reaction vessels integratedwith fuel cells in accordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

As an exemplary embodiment of the present invention consider the pair ofreactors 10 and 10A shown in FIG. 1, which are designed to producehydrogen. These reactors are identical. Corresponding elements of thetwo reactors are given the same reference numerals, except that thenumerals are followed by the letter A for elements of the right-handreactor. The reactors 10 and 10A operate in conjunction with each other,such that while one is in the "make mode" (i.e., making hydrogen) theother is in the "regeneration mode" (i.e., being regenerated). After asuitable period of time the reactors switch modes. Thus, at any point intime, one of the reactors is making hydrogen while the other reactor isbeing regenerated. Of course, if a continuous flow of hydrogen gas isnot required, then only a single reactor could be used. Hereinafter theoutput from the reactor in the make mode is sometimes referred to as the"product gas" or "reform products". For the purposes of explanation, thereactor 10, on the left, is considered to be in the make mode, and thereactor 10A on the right is in the regeneration mode.

The reactor 10 is shown as comprising a cylindrical reaction vessel 12.At the bottom end of the vessel is a steam and hydrocarbon feedstockinlet 14 and a combustion products outlet 16. At the top end of thevessel is a product gas outlet 18 and a hydrogen purge gas andcombustion products recycle inlet 22. On the side of the vessel is anoxygen containing gas inlet 20. In this embodiment, the oxygencontaining gas is air. Flow into inlets 14 and 20 is controlled byvalves 30 and 32, respectively. Flow into inlet 22 is controlled byvalve 34. Flow from the outlets 16 and 18 is controlled by valves 36 and38 respectively. As shown in the drawing, during the make mode, thevalves 30 and 38 are open while the valves 32, 34, and 36 are closed.

From an operational point of view, the vessel 12 may be thought of ascomprising three zones arranged in sequence or series gas flowrelationship within the vessel. The zones are labeled zone 1, zone 2,and zone 3 in the drawing. Imaginary lines L₁ and L₂ have been drawn infor the purpose of visualizing and discussing where one zone ends andthe next begins, although in actual operation the point where one zoneends and the next begins cannot be so precisely defined.

During the make cycle a mixture of steam and hydrocarbon feedstockenters zone 1 of the reactor vessel 12 via the inlet 14. Zone 1 isfilled with an inert packing material 39, such as alumina, which hasheat stored therein from the regeneration cycle. The mixture of steamand feedstock entering zone 1 are at a lower temperature than thetemperature of the packing material, and thus heat is transferred to themixture from the packing material as the mixture passes through zone 1.The hydrocarbon feedstock may be either in the form of a gas, such asnatural gas, or in the form of a vaporized liquid hydrocarbon, such asnaptha, No. 2 heating oil, or the like. For those hydrocarbon feedstockswhich may be difficult to vaporize, the feedstock may preferably beinjected or sprayed into zone 1 or at the exit of zone 1 using thesensible heat in the preheated steam and heat stored in the packing toachieve complete vaporization.

The end of zone 1 is considered to be that location within the vessel 12wherein the steam and feedstock mixture have been heated to atemperature high enough such that cracking and/or reforming of thefeedstock begins to occur. At this point the mixture is considered to beentering zone 2. Thus, zone 1 may be thought of as a preheating zoneduring the make mode. Within zone 2, cracking and reforming of thefeedstock takes place. The temperature at the inlet of zone 2 willprobably be somewhere between 370° C. and 540° C., depending upon thefeedstock being used and the material within the reactor (i.e., inert orcatalytic). In this embodiment, zone 2 is divided into two regionslabeled region 1 and region 2. Disposed within region 1 is packingmaterial and preferably a nonoxidizable reform catalyst, and in region2, which is immediately downstream of and in series gas flowrelationship to region 1, is reform catalyst 42. The reform catalystwill typically be a metal supported on an inert ceramic material. Forexample, a common reform catalyst is nickel supported on alumina. Thecatalyst or packing material 40 in region 1 may be, for example, a noblemetal catalyst supported on a refractory support like alumina, ormagnesium oxide pellets, or may be the same as the material 39 inzone 1. The packing material 40 will be, on average, considerably hotterthan the material in zone 1 as a result of combustion taking place inregion 1 during the regeneration mode. As the effluent from zone 1travels through region 1 of zone 2, the heat needed for gasification isprovided by the sensible heat in the material 40. The temperature of theeffluent from region 1 is sufficiently high to provide the heat requiredfor the additional reforming of the hydrocarbon feedstock (within region2) without adding heat from external sources.

The end of zone 2, which is the beginning of zone 3, is considered to bethe location within the reaction vessel 12 wherein no furthersubstantial gasification or reforming takes place. Zone 3, in thisembodiment, contains only inert packing material, and is cooling zneduring the make mode. As the effluent from zone 2 is cooled, ittransfers heat to inert packing material disposed in zone 3. The lengthand volume of zone 3 is preferably selected so as to cool the effluentfrom zone 2 to a preselected temperature. The cooled effluent is thenexhausted from the reaction vessel 12 via the outlet 18. This effluentis the reactor product gas. In addition to hydrogen it contains carbonmonoxide, carbon dioxide, methane and water.

Although not the case in this embodiment, zone 3 may include a region ofshift catalyst in place of a portion of the inert packing material.Within the shift catalyst region carbon monoxide and water in theeffluent from zone 2 would combine to produce additional hydrogen andcarbon dioxide in a manner well known to those skilled in the art. Thisis very desirable when the product gas made in the reactor 10 is to beused in a phosphoric acid electrolyte fuel cell which cannot toleratemore than a few percent of carbon monoxide. If desired the carbondioxide could be removed downstream of the reactor using well knownscrubbing devices; but this is not necessary if the product gas is to beused in a phosphoric acid electrolyte fuel cell.

Turning now to the regeneration cycle which is occurring in reactor 10A,the valves 30A and 38A are closed and the valves 32A, 34A, and 36A areopen. A hydrogen purge gas (i.e. anode exhaust, fuel electrode exhaust)which had been mixed with combustion product recycle (recycledcombustion exhaust products) (see below) from outlet 16A enters thereaction vessel 12A via the inlet 22A. The combined gases travel throughthe inert packing material 46A in zone 3 picking up heat therefrom. Thecombined hydrogen purge gas and combustion product recycle molar flow isselected so as to effectively cool the packing material that was heatedduring the make cycle. Thus, an mount of combustion products arerecycled that have a heat capacity sufficient in conjunction with thepurge gas to cool the make stream to the temperature desired for theparticular application. The combined flow is typically about 0.8 toabout 1.2 mole per mole of product gas. Below about 0.8 mole per mole,there will be insufficient cooling to recover the process heat in thereform products resulting in the reform products exiting at too high atemperature. Above about 1.2 mole per mole, there is too much coolingresulting in the reform products and reformer being cooled too much.Preferably, about 0.9 to about 1.0 mole per mole is used as thisprovides sufficient cooling in an efficent manner. This is because thespecific molar heat capacity of the burner recycle tends to be slightlyhigher than that of the product gas. With fuel cell applications, themolar flow should be sufficient to cool the make stream from atemperature range of about 870° C. to about 1100° C. to a temperaturerange of about 200° C. to about 315° C. The packing material 46A isthereby cooled somewhat during the regeneration cycle. It is, of course,reheated during the make cycle when it performs the function of coolingthe product gases.

Air (optionally preheated through heat exchange with combustion productexhaust) enters the vessel 12A via the valve 32A. The air enters fromthe inlet 20A located between regions 1 and 2. Regions 1 and 2 areseparated by a cylindrical ceramic (refractory) insert or wall 60through which the air enters, and a catalyst support plate 61 whichretains catalyst 42 in region 2. A typical insert 60 material isalumina. A typical catalyst support plate 61 material comprises aluminaor fully stabilized zirconia. The air mixes with the hydrogen purgegas/combustion product recycle from zone 3 which has just passed throughthe reform catalyst in region 2 and combusts in area 65. Air additionmay also be staged (introduced at various points) to allow combustion attwo or more points (areas) within region 1. This produces regions ofdifferent combustion stoichiometry or fuel richness in region 1 which isadvantageous because different catalyst materials can be used at thedifferent points. The catalyst can be selected which is best suited foroperation at each stoichiometry (without becming oxidized duringregeneration). If the catalyst were to become oxidized, this wouldresult in loss of some of the hydrogen being manufactured (during themake cycle) as the catalyst is re-reduced, hence less efficiency. Thequantity of air entering should be equal or have just slightly less thanthe stoichiometric amount of oxygen required to completely burn thehydrogen and any other combustibles contained in the hydrogen purge gas.This assures a hydrogen rich operation mode in which the combustionproducts contain no oxygen so that when recycled and mixed with thehydrogen purge gas, there is no possibility of combustion downstream ofregion 1. As combustion occurs, and as the combustion products travelthrough zone 2 and zone 1 and are eventually exhausted via the outlets16A and 44 (and optionally catalytically burned with additonal air oroxygen later), heat is transferred to and stored in the packing material40A and 39A. It is this stored sensible heat within the reaction vesselwhich is used to preheat, crack and reform the hydrocarbon feedstockduring the reactor's make mode of operation.

The fuel processing apparatus of the present invention can provide thefuel for a fuel cell or for a stack of fuel cells. One possible fuelcell system is shown schematically in FIG. 2. During operation, ahydrocarbon feedstock and steam from any suitable source 212 passesthrough an open valve 214 and enters the reform reactor 200 which is inthe make mode. The feedstock and steam are converted to hydrogen withinthe reactor 200. The hydrogen containing reform gas leaves the reactor200 via the conduit 218 and is directed to the anode electrode (fuelelectrode) 206 at the fuel cell 204. Anode exhaust (fuel electrodeexhaust), which contains unconsumed hydrogen leaves the cell via aconduit 224, mixes with recycled combustion product gas which entersconduit 224 from conduit 230 and is directed into the reactor 202 by wayof conduit 226. The anode exhaust (hydrogen purge gas) and the recycledcombustion product exhaust are used for regeneration as hereinbeforedescribed. Air from a suitable source 228 passes through an open valve280 and enters the reactor 202 via a conduit 232. Within the reactor 202the air from conduit 232, the anode exhaust and recycled combustionproduct exhaust from conduit 226 combine and burn in accordance with thepresent invention as hereinabove described, and the combustion productsare exhausted from reactor 202 through open valve 236. A portion of thecombustion products are recycled through conduit 230 and some areexhausted through conduit 250. Those skilled in the art will readilycomprehend that the system described above can be reversed such that thefunctions of the two reactors are switched in a like manner to thatdescribed in commonly-assigned U.S. Pat. No. 4,200,682.

EXAMPLE

Referring to FIG. 2, a mixture of 1 mole of CH₄ and 3 moles of H₂ O arefed at a temperature of 200° C. to the make reactor 200 via conduit 212.About 6 moles of reform products consisting principally of CO, CO₂, H₂and H₂ O are produced achieving a temperature of 925° C. before coolingin cooling zone 3 (described previously in FIG. 1) and exiting reactor200 via conduit 218 at a temperature of 260° C. The heat capacity ofthese reform products is approximately 50 calories per degreecentigrade. These reform products are fed to a fuel cell anode (fuelelectrode) where 3 moles of H₂ are consumed electrochemically to produceelectrical power. These reform products, now partially depleted of H₂exit the fuel cell anode (fuel electrode exhaust) via conduit 224 at atemperature of 200° C. with a heat capacity of approximately 28 cal/°C.This heat capacity would be insufficient to adequately cool the packingmaterial in zone 3 heated in the process of cooling down the 50 cal/°C.reform product from 925° C. to 260° C.

In this example, combustion products having provided heat to thecatalysts and packings for the steam reform process exit reactor 202undergoing regeneration via valve 236 at a temperature of about 315° C.A portion of the combustion products are recycled by means of a recycleblower 260 via conduit 230 through a heat rejection heat exchanger 240and cooled to about 200° C. A recycle corresponding to a heat capacityof 22 cal/°C. which corresponds to about 50% of the combustion productsexhaust leaving the system via conduit 250 is required to complement thefuel electrode exhaust heat capacity of 28 cal/°C. to provide cooling ofzone 3. The recycled combustion products are mixed with the fuelelectrode exhaust and fed to reactor 202 via conduit 226 at atemperature of 200° C. This mixture having a total heat capacity ofapproximately 50 cal/°C. is heated from 200° C. to 870° C. within zone 3and provides the required cooling of the reform products formed duringthe alternate make cycle. More or less recycle flow will result in moreor less cooling of the reform products and a correspondingly higher orlower temperature of the reform products exiting reactor 200 via conduit218.

The combustion products exiting the system via conduit 250 may containunburned H₂ and CO. Normally, a small amount of air would be addeddownstream to allow catalytic combustion of these unburned gases. Theresultant combustion products would then be cooled further to recoveradditional process heat.

The fuel conversion apparatus of the present invention can also beutilized for the generation of hydrogen for other applications such asthe chemical process industry. Purge gas containing hydrogen from achemical process or a portion of the hydrogen containing gas produced bythe make reactor (approximately 25%) can be used for the regenerationprocess. This purge gas combined with recycled combustion products canbe used to cool the reform product gas and provide the heat required forthe steam reform process. Since heat is transferred in this process bydirect contact with catalysts and packings, rather than through thewalls of a tubular metallic reactor as is practiced in conventionalsteam reforming furnaces, the process is capable of operation attemperatures and pressures above conventional systems (using aninternally lined vessel with cast insulation). This allows theachievement of high fuel conversion at high pressure with reduced syngascompression costs for methanol and ammonia production.

This system can achieve the same high efficiencies as previous cyclicreformer systems without the use of cooling air tubes (conduits). Thesetubes are expensive to manufacture, difficult to manifold and assembleinto the reactor and complicate filling of the reactor with catalyst andpacking materials. These tubes are also subject to a temperature cycleand a varying gas composition environment which can lead to distortion,corrosion and reduced tube life. Operation at high temperatures (whichis required to achieve high fuel conversion with high sulfur contentfuels) further compounds these problems. The elimination of air tubeshas been accomplished by recycling combustion products in a systemoperating in a hydrogen rich mode. The recycle increases the coolingcapacity of the regenerating hydrogen purge gas stream. Sufficientcooling is required to lower the temperature of the hydrogen make streamand recover the heat remaining in the cyclic reformer bed following thehydrogen make cycle to optimize cyclic reformer performance. In summary,this invention makes a significant contribution to the cyclic reformerart by simplifying reactor bed design and improving operationalflexibility.

It should be understood that the invention is not limited to theparticular embodiment shown and described herein, but that variouschanges and modifications may be made without departing from the spiritor scope of this concept as defined by the following claims.

I claim:
 1. Reaction apparatus constructed to alternately:(a) make ahydrogen containing gas by the cracking and catalytic steam reforming ofa hydrocarbon feedstock; and (b) be regenerated, comprising: at leastone reaction vessel having an upstream end and downstream end, saidvessel having disposed therein, in sequence from its upstream todownstream end, a first volume of inert packing material containing noreform catalyst, a second volume of material substantially adjacent saidfirst volume and including a region of reform catalyst material and athird volume of material substantially adjacent said second volume; saidvessel including first inlet means upstream of said second volume forintroducing a hydrocarbon feedstock and steam into said first volumeduring the making of the hydrocarbon containing gas, and first outletmeans at said downstream end of said vessel for exhausting the hydrogencontaining gas produced in the vessel; said vessel including secondinlet means at its downstream end for introducing a hydrogen purge gasinto said third volume during the regeneration of the apparatus, andsecond outlet means at said upstream end for exhausting combustionproduct gases produced during regeneration; said second inlet meansincluding third inlet means for introducing a portion of said combustionproduct exhaust gases produced during regeneration into said vessel; andsaid vessel including fourth inlet means within said second volume ofmaterial located upstream of said region of reform catalyst forintroducing an oxygen containing gas.
 2. The reaction apparatus of claim1 wherein the second volume includes a region containing a nonoxidizablereform catalyst upstream of said reform catalyst region.
 3. In a methodfor producing a hydrogen containing gas from a hydrocarbon feedstock andstream in a reaction vessel, said vessel including three zones in seriesgas flow relationship, the steps of:alternately making a hydrogencontaining gas in the reaction vessel and regenerating the reactionvessel, wherein the step of making gas includes: (a) preheating, in afirst of said zones, at least the steam or a mixture of both the steamand feedstock using sensible heat stored in material disposed withinsaid first zone, the stored heat in said first zone having been providedby said regenerating step; (b) cracking and reforming, in a second ofsaid zones substantially adjacent and downstream of said first zone, amixture of said feedstock and said preheated steam, using the sensibleheat in the preheated steam and the sensible heat stored in materialdisposed within said second zone, thereby producing the hydrogencontaining gas, the stored heat in the second zone having been providedby said regenerating step, said second zone including a region of reformcatalyst; (c) cooling the hydrogen containing gas made in said secondzone by passing said gas through a third of said zones which issubstantially adjacent and downstream of said second zone andtransferring heat from said gas to material disposed within said thirdzone; and (d) exhausting, from the reaction vessel, said hydrogencontaining gas; and wherein the step of regenerating includes: (e)preheating within said third zone, a hydrogen purge gas and combustionproduct recycle gas from step (j) using the sensible heat in thematerial disposed within said third zone, the heat in said third zonebeing provided by step (c); (f) directing an oxygen containing gas intosaid second zone located upstream of said region of reform catalyst; (g)mixing, within said reform catalyst region, said oxygen containing gaswith said preheated hydrogen purge gas and combustion product recyclegas from said third zone, and combusting said mixture upstream of saidregion of reform catalyst; (h) cooling the products of combustion fromsaid second zone by passing said products through said first zone andtransferring heat from said products to material disposed within saidfirst zone; and (i) exhausting from the reaction vessel, said cooledcombustion products; (j) recycling a portion of the exhaust products ofcombustion step (g) and mixing said exhaust combustion products with thehydrogen purge gas of step (e).
 4. The method as recited in claim 3wherein the second zone includes a region containing a nonoxidizablereform catalyst upstream of said reform catalyst region.
 5. A fuel cellsystem comprising:(a) a fuel cell including a fuel electrode, an oxygenelectrode, and an electrolyte disposed therebetween; (b) a pair ofreaction vessels, each being adapted to alternately make a hydrogencontaining gas and to be regenerated, each of said reaction vesselshaving an upstream end and a downstream end, each vessel having disposedtherein, in sequence from its upstream to downstream end, a first volumeof inert packing material containing no reform catalyst, a second volumeof material including a region of reform catalyst material, and a thirdvolume of material; (c) means for alternately directing a hydrocarbonfeedstock and steam first into said first volume of one of said vesselsand then into said first volume of the other of said vessels; (d) meansfor directing the hydrogen containing gas produced in the one of saidvessels receiving said feedstock and steam into said fuel electode ofsaid fuel cell and for directing the exhaust from said fuel electrodeinto said third volume of material in the other of said vessels; (e)means for directing an oxygen containing gas into said vessels includingan inlet means upstream of said region of reform catalyst; (f) each ofsaid vessels including combustion products outlet means at its upstreamend for exhausting combustion products therefrom during regeneration ofeach vessel; and (g) means for directing a portion of said combustionproducts into each of said vessels including an inlet downstream of saidregion of reform catalyst.
 6. In a method for providing a continuoussupply of hydrogen fuel to a fuel cell from a pair of reaction vessels,said fuel cell comprising a fuel electrode, an oxygen electrode, and anelectrolyte disposed therebetween, the steps of alternately:A. makinghydrogen fuel in one of said pair of vessels while simultaneouslyregenerating the other of said pair of vessels; and B. regenerating saidone of said pair of vessels while simultaneous making hydrogen fuel insaid other of said pair of vessels;wherein steps (a) and (B) eachcomprise steps of: (a) introducing a hydrocarbon feedstock and steaminto a first of said vessels, which is making hydrogen; (b) cracking andsteam reforming said feedstock to make said reform products includinghydrogen in said first vessel using sensible heat stored within saidfirst vessel, said sensible heat being obtained from the step ofregenerating said first vessel; (c) directing the hydrogen produced instep (a) to the fuel electrode of the fuel cell; (d) introducing airinto the oxygen electrode of the fuel cell; (e) directing the exhaustfrom the fuel electrode, recycled combustion exhaust products of step(h) and an oxygen containing gas into the second of said vessels, whichis being regenerated, said oxygen containing gas having slightly lessthan the stoichiometric amount of oxygen required to completely combustany hydrogen of the fuel electrode exhaust; (f) preheating said fuelelectrode exhaust and recycled exhaust products to temperatures highenough to result in combustion of said oxygen containing gas, said fuelelectrode exhaust and recycled combustion exhaust products if they aremixed together; (g) mixing said oxygen containing gas, said preheatedfuel electrode exhaust and said recycled combustion exhaust productswithin said second vessel and combusting said mixture within said secondvessel to regenerate said second vessel by storing within materialdisposed within said second vessel heat from said step of combusting,wherein said step (f) of preheating is accomplished using the heat fromsaid step of combusting and/or sensible heat stored within said secondvessel; (h) exhausting the products of combustion of step (g) from saidsecond vessel; (i) recycling a portion of the exhaust products ofcombustion step (g) and mixing said exhaust combustion products with thefuel electrode exhaust of step (e).